Nowadays, information is highly centralized, and a telephone switch system frequently faces a burst of traffic peak. For example, during a certain period in a holiday or after a regional outburst event occurring, a large number of call requests congest local telephone networks, and then a calling connection may not be completed for a long time. Sometimes even the switch needs to reset its system, which not only interrupts emergency calling connection, but also directly affects service quality and equipment maintenance of switch system.
Traffic load is often controlled by a method of sharing traffic load in current techniques to promote flow of centralized burst traffic. But when an overflowed route is not idle and its certain calls are overflowed too, this method is unable to process the overflow traffic. On the contrary, network congestion can be aggravated by the method, when heavy overflow traffic occurs. Thus, this method is obviously not suitable for current complex and changeful traffic structure.
The same problem described above, namely how to control traffic load effectively, is faced in soft switch system that is the core equipment developing from circuit switching network to packet switching network, an important system in next generation of telecommunication network.
A prior art most related to the present invention is U.S. Pat. No. 5,933,481, which discloses “a method of controlling call traffic in a telecommunication system”. The invention provides a method of dynamically altering the rate at which incoming offered calls are accepted, including the step of successively determining the offered call rate of the incoming offered calls. In this method when the offered calls increase, the system accepts the calls at a lower rate. For two gapping intervals used by the invention, the shorter gapping interval is used to accept the calls when the offered call rate is no greater than a set value; the longer gapping interval is used to accept the calls when the offered call rate exceeds the set value.
However, there are disadvantages in this method as follows:
A fluctuation can happen when processing burst calls, either accepting calls beyond system process capacity, or refusing some calls when system is able to accept calls. For example, within a short period of time, the system offers calls beyond system process capacity, and then subsequently the system could not offer any calls at all.
In a practical application, the load accepted by a system generally happens for a short time, which can't cause system congestion. Thus, all of offered calls can be processed by the system. If too many calls is continuously received within a period of time, the system should refuse to process some of the calls, in which, furthermore, the refused calls should not be emergency calls for special services.
The present invention provides a method of controlling call traffic load in an IP network to overcome current technical disadvantages.